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state Rea. <br />major cations, and sulfate oars in hider concentrations, beomning <br />the daninant anion. 7.AS concentrations also increase downstream. <br />Samples collected at we1Ls 6-A and 31 A2 have M9CaNa-504 ctrl Cam-~4 <br />water types, respectively. ZDS concentrations at these sites have <br />been steadily increasing; the hic~est 'II)s value was 3540 mg/1 <br />~a~TMed at 31 A2 during the 1991 water year. <br />Water samples collected at well 33 A, ocmg~leted in the (Massy Creek <br />alluvium, have a CaMg-504 water type. Z9.S values at this site have <br />also been increasing in recent years, with a peak value of 1694 mg/1 <br />~++pas+TMed on 10/27/90. However, ZDS oonoentrations are ar*~*-~yi~tely <br />50 percent lacer than those ~~~**'ed in the Little (Massy Creek <br />aquifer, suggesting that Little GYassy Creek alluvial waters are <br />diluted when the (Massy Creek alluvium is encountered. <br />Fish Creek Alluvial Swstem. Although no monitoring wells are <br />omnpleted in the Fish Creek alluvium, Peabody does maintain three <br />• wells that monitor the alluvitnn of tributaries to Fish Creek. Wells <br />'46-A ctrl 69 A are cong~leted in the Oow Camp Creek alluvium, and well <br />68 A is completed in the Bowl Creek alluvium. Of the three wells, <br />only 46 A was oonstziicted before mining occurred upgradient fran its <br />location; this well was first sampled on 11/10/82, approximately one <br />year priar to mining. <br />Water types at all three wells are similar, with sulfate as the <br />dominant anion and calcium or magnesium as the dominant cation. <br />Fatly data collected at 46-A indicates that pr amin;r~ Cow Camp Creek <br />alluvial water quality was poor since 79.5 concentrations ranged from <br />^ 2068 to 2300 irq/1 before minittl. TY~is as.~mg>tion is supported by the <br />/ IL hick Zfls measurements that have been measured at Spring #5 (as hick <br />° as 14 200 sp ing upstr <br />m7/1), a natural r located eam of 46-A. TDS <br />values have been declinim at 46-A since 1986. <br />Bond Creek alluvium '19S wnoentrations are significantly hider than <br />those of the Cow Camp Creek alluvium. ZWo samples wllected at well <br />68-A during the 1991 water year had an average Z9,S of 5089 mg/1, <br />7-314 Revised 12/10/92 <br />